The invention relates to an expansion anchor comprising an elongated main part, which has a substantially longitudinally extending receiving area into which an expansion element is inserted in the longitudinal direction in order to press the expansion tabs laterally from a starting position to an expanded position.
Expansion anchors are used to fix components to a main part. For this purpose, the main part element of the expansion anchor has expansion tabs, which after insertion of the expansion anchor into a hole can be spread laterally and thus clamp the expansion anchor into the hole. For this purpose, an expansion element is typically provided, which is stored in the expansion anchor so that it can move longitudinally, and when moved pushes the expansion tabs sideways into a spread position. A disadvantage of the previously known expansion anchors is that after insertion of the expansion anchor into the main part, it is not possible to control whether the expansion tabs are sufficiently expanded in order to achieve a sufficient clamping effect.
The objective of the invention is to create an expansion anchor of the aforementioned type, which offers better verification of expansion properties in the installed state.
To achieve the objective, in an expansion anchor having an elongated main part with a receiving area substantially extending in the longitudinal direction, into which an expansion element is longitudinally inserted to push the expansion tabs laterally from a starting position to an expanded position, at least one setting control element exists, which is provided in the longitudinal direction of the expansion anchor, and is shifted by movement of the expansion element relative to the main part with the latter. The position and location of the expansion tabs cannot be controlled if the expansion anchor is pushed in. The expansion element action of the expansion tabs can be determined in advance as a function of the position of the expansion element. However, the position of the expansion element when pushed in cannot be determined with sufficient precision. For this reason, a setting control element is provided, which is displaced during insertion of the expansion element with the latter, whereby the position change of the expansion element is determined from the outside. Because the setting control element does not need to transfer any forces, such as expansion forces, it can be made very easily and after engagement of the expansion anchor after the expansion action, can be at least partially removed, so that the expansion anchor closes flush with the surface of the component.
Preferably, the setting control element is made longitudinally. The setting control element can thus easily be stored longitudinally or in the receiving area, so that easy longitudinal movement is possible. To facilitate control of the insertion depth of the expansion element, the setting control element can, for example, in the home position of the expansion element, extend from the main part element and, in the spread position, not extend from the rear from the main part element. That means that easy control of the position of the expansion element is possible, since for a correctly used expansion element the setting control element no longer projects from the receiving area or is not even visible.
So as not to impair the movement of the expansion element in the main part, the main part has one substantially axially extending channel or one recess, in which at least one setting control element is guided to move. The channel or the recess is formed so that the setting control element is guided outside the movement path of the expansion element, whereby the expansion element and the setting control element cannot become jammed. Thus an impairment of the function of the expansion anchors can be excluded with certainty.
This channel or recess can adjoin the receiving area, i.e., form a groove emerging from the receiving area, thus permitting easier manufacturing of the recess or the channel.
The receiving area of the expansion anchor can have a thread, into which the expansion element with the matching thread can be screwed, whereby precisely controlled insertion of the expansion element and thus precise insertion of the expansion element to the desired insertion depth in the receiving area is enabled. The channel or the recess preferably adjoin the thread. That means that the channel or the recess and thus the therein extending setting control element do not project into the thread, so that the expansion element can be moved unhindered into the receiving area.
The channel or the recess extends at least from the thread base and divide the thread into sections, so that the setting control element is guided outside of the thread and does not project into it.
The channel can further be used for easier manufacturing of the thread. Normally, in order to cut, the cutting tool turns such a thread into the receiving area over several windings, whereby only one thread rotation can be cut per rotation. The thread cutter must then again be fully retracted from the receiving area, and the newly cut thread must be screwed out. Through the channel or the recess, a cutting tool with a plurality of longitudinally extending cutting edges situated one behind the other can be used, which can, with the cutting edges, be guided into the receiving area completely by the cutting edges without turning, axially via the channel(s) or recess(s). To cut the thread, this tap, after insertion into the receiving area, is turned along its longitudinal access, until the cutting edges again lie in the next recess or channel in the circumferential direction. With this, each of these cutting edges has cut a complete thread rotation of the thread, whereby all cut thread rotations together make up a complete thread. Because the cutting edges again lie in the recess or the channel, the tap is then simply removed from the receiving area in the axial direction. It is also possible to cut the total length of the thread with a maximum of one single rotation of the tap. After cutting of the thread, the recess or channel can be used to guide the setting control element.
It is also possible that a plurality of setting control elements are provided, which are, in particular, evenly arranged in the circumferential direction. These can, for example, be assigned to individual expansion tabs, so that more precise verification of the position of the expansion elements and thus the expansion tabs is possible.
If a plurality of setting control elements are used, they can be connected to each other such that they are jointly moved by the expansion element.
On the expansion element, a cam is provided, for example, which projects into the movement path of the expansion element and is connected or can be coupled thereto. This cam may be a ring, for example, into which a tip of the expansion element projects. The expansion element takes this ring moving in a longitudinal direction and thereby shifts the setting control elements.
The setting control element may for example be so coupled to the expansion element, so that the setting control element upon insertion of the expansion element is displaced with the latter, but is retained by a release of the expansion anchor by withdrawing the expansion element, in the recording. But it is also conceivable that the setting control element is fixedly coupled to the expansion element and upon retraction of the expansion element is again withdrawn from the receiving area together with it. This allows, on the release of the expansion anchor, a visual inspection of whether the expansion element was withdrawn to a sufficient width to reduce the expansion effect, so that the expansion anchor can be pulled out of the hole. In addition, the expansion anchor can be used multiple times.
The setting control element can for example also form a unit in advance and be firmly attached to the expansion element, so that they are not detachable from each other.
The fixation is for example formed by the cam being mounted on a shoulder or a groove on the expansion element.
The cam and at least one setting control element are, for example, one-piece, in particular made of sheet metal, thereby permitting easier manufacturing of this setting control element. The setting control elements can extend, for example, in a star shape by an annular cam, and will be bent at right angles before placement in the main part of the expansion anchor prior to insertion.
On the expansion anchor, an expansion element is preferably provided, which in particular has a tapered tip. During insertion of the expansion element into the main part, this tip forces the expansion tabs laterally into the expanded position. The expansion tabs, in order to reinforce this expansion effect, have a corresponding tapered shape so that a larger expansion effect can be achieved.
Other advantages and features can be found in the following description in conjunction with the accompanying drawings.